Label-free low-level detection of human chorionic gonadotropin using a multicomponent 2D/0D ternary nanohybrid-based biosensor

Human chorionic gonadotropin (hCG), a clinically critical biomarker for pregnancy and malignancies such as bladder, ovarian, and prostate cancers, demands rapid, ultrasensitive detection platforms to overcome limitations of conventional laboratory-dependent techniques with prolonged turnaround times. This article presents an electrochemical immunosensor leveraging a multicomponent 2D/0D ternary nanohybrid (MoS2/gC3N4/CDs) engineered for charge-transfer-driven signal amplification. This innovative architecture synergizes the catalytic performance of 2D MoS2 nanosheets, the redox-active matrix of gC3N4, and the high conductivity/functional surface sites of 0D CDs, enabling efficient electron transport, enhanced antibody immobilization, and ultrasensitive analyte recognition. The biosensor achieves exceptional performance metrics such as a detection limit of 1.5 � 10?2 ng mL?1, a quantification limit of 5.2 � 10?2 ng mL?1, and a wide linear dynamic range (1.0 � 10?4 to 80 ng mL?1) with a sensitivity of 0.76 ?A [log10(ng mL?1)]?1 cm?2. Remarkably, the assay completes within 3 min, a 90 % reduction in analysis time compared to conventional ELISA and chemiluminescence assays. The platform demonstrated low signal deviation in spiked human urine samples, with 99.5 % recoveries and negligible cross-reactivity against interfering biomarkers. The nanohybrid's defect-rich interfaces and ?-? stacking interactions facilitated stable biofunctionalization, while CDs minimized MoS2 aggregation, preserving electroactive sites. This design outperforms prior MoS2 or gC3N4-based sensors in sensitivity and response time. This label-free, portable biosensor offers a transformative solution for POC hCG monitoring, with direct applications in early cancer diagnosis, prenatal care, and real-time therapeutic tracking. Its modular architecture can be adapted for other biomarkers, underscoring broad potential in precision medicine.